The heat produced by electronic elements in various electronic devices increases with the increasing computing speed and data processing capability of the electronic devices. The heat produced by the electronic elements during the operation thereof must be timely removed, lest the heat should adversely affect the operation efficiency of the electronic devices to even cause burnout of the electronic elements thereof. According to a conventional way of removing such heat, a cooling unit is provided on a top of an electronic element. The conventional cooling unit usually includes a heat sink or a plurality of radiating fins and a cooling fan, which work cooperatively to remove the produced heat. In some cases, heat pipes are further provided to cooperate with the cooling unit, so that heat source is guided by the heat pipes to distal ends of the heat pipes and be dissipated into ambient environment. However, since an electronic device usually has only very limited internal space while the number of heat-producing electronic elements in the electronic device is large, the cooling units being correspondingly provided on the electronic elements will become very close to one another in the limited internal space of the electronic device and fail to extend their cooling ability. There is also another conventional heat dissipating way in which heat pipes are embedded in one face of a heat dissipating board to thereby form a heat dissipating element capable of overcoming the drawbacks in the conventional cooling unit and heat pipes. The conventional heat dissipating board includes at least one groove formed on one face of the board for each receiving a heat pipe therein. The heat pipe transfers the heat source to a relatively cold location on the heat dissipating board, so that the heat is dissipated into ambient air from the heat dissipating board. To facilitate easy positioning of the heat pipe in the groove, the groove is usually formed with a somewhat large allowance. Therefore, there would be a clearance left between the groove and the heat pipe positioned therein. Such clearance tends to cause thermal resistance to adversely affect the heat dissipation efficiency of the conventional heat dissipating board. Further, when the heat pipe is associated with the groove through welding, the heated surface of the heat pipe will expand to adversely affect the accuracy in assembling the heat pipe to the groove. In brief, the conventional heat dissipating board has the following disadvantages: (1) poor heat dissipation efficiency; and (2) poor assembling accuracy.